6 SPHAGNACEjE. 



serrulate above, margined only with a single row of very narrow 

 cells, often rendered absent by erosion. Hyaline cells rather 

 large, with large pores ; the walls smooth. Chlorophyllose cells 

 in section narrowly oval-triangular , on the ventral face of the 

 leaf, hardly reaching the dorsal face, but somewhat variable in 

 both form and position. 



Var. /3. squarrosulum Nees & Hornsch. Deeper green. 

 Branch leaves more pointed, patulous ; those of the comal 

 branches squarrose. 



Var. y. congestum Schp. Short ; densely tufted ; variously 

 tinted. Upper cells of stem leaves oilers, fibrose. Branches short, 

 thick, obtuse ; the leaves closely imbricated. 



Hab. Bogs and sides of streams and pools, common. The var. P in woods 

 and by the borders of pools. The var. y on drier moors. 



Sphagnum cymbifolium in its typical form is not likely to be confused with any 

 other species but 5. papillosum and S. Austini, from which it can hardly be certainly 

 distinguished without microscopic examination. It has, however, less often the 

 yellowish brown tinge of J. papillosum, which is also a more rigid plant. S. Austini 

 is moreover extremely rare. The robust habit with large tumid branches will dis- 

 tinguish it almost at first sight from most of the other species. The vars. might be 

 taken, the one for a form of .S. squarrosum, the other for S. rigidum var. compactum ; 

 but a little attention to the form of the leaves will soon dispel all doubt. 



It may be noted here, with reference to the fibrose cells of the stem leaves in the 

 var. congestum, that this character usually prevails in the more compact forms of the 

 various species. As the function of the fibres is supposed to be to maintain the form 

 of the cell by the additional support they give to the cell wall, their presence in 

 greater numbers would naturally be looked for in those forms whose dense growth 

 submits the cells to greater pressure. 



S. medium. Limpr., a species, or rather a sub-species of S. cymbifolium not at 

 present recorded from this country, differs (mainly) in having the chlorophyllose cells 

 small and immersed half-way between the back and front of the leaf, with the hyaline 

 cells meeting one another both above and below. It has recently been found in 

 France, and appears to be as widely distributed as S. cymbifoliutn in some parts of 

 N. America, while in Scandinavia it is, according to Lindberg, the commonest 

 species of the section Cymbifolia, the true S. cymbifolium being very rare. 



* Sphagnum papillosum Lindb. (S. cymbifolium var. papil- 

 losum Schp. Syn.) (Tab. VI. B.) 



Differs from S. cymbifolium in the plant being 'usually of an 

 ochraceous tinge, without trace of purple ; in the more rigid and 

 more obtuse branches, and especially in the walls of the hyaline 

 cells of the branch leaves, where they adjoin the chlorophyllose, 

 being more or less covered with small conical papillae. The upper 

 part of the branch leaves is also less frequently narrowed, giving 

 the whole a broader and rounder outline, and the margin is some- 

 what more distinctly serrulate. 



